A
common wear item on BMWs over a period of time is the drivetrain guibo.
The guibo serves as an interface between the transmission and the driveshaft.
Since the guibo is primarily made from rubber, it acts as a damper when shifting
and engaging into gears, so that the transfer of power to the driveshaft is
smooth and dampened, instead of abrupt and harsh.

Replacement of the guibo depends on age and
driving style. We have seen vehicles less than 12 months old with 15,000
miles that had already started developing cracks around the bolt holes. We
have also seen vehicles over 5 years old and over 100,000 miles with guibos
without any stress cracks whatsoever. Needless to say, if you drive your
car aggressively, your guibo may have to be replaced sooner than others.

Without a visual inspection of the guibo
itself, an audio sign that the guibo may have started to crack is a
"clicking" noise under specific circumstances. Below is a method
we've been able to replicate the "clicking" sound.

Step
1:

Find a straight,
downhill section of road that will allow you to maintain vehicle speed of
between 15-25 mph.